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Updated: Jun 14, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photodetachment of tryptophan anion: an optical probe of remote electron
Isabelle Compagnon1, Abdul-Rahman Allouche, Franck Bertorelle
1Université de Lyon, Université Lyon 1, CNRS, UMR5579, LASIM, 69622 Villeurbanne, France.
Abstract:
The UV photoexcitation spectrum of deprotonated tryptophan anion is presented. Singly deprotonated amino-acid tryptophan has been produced in an electrospray ionization source, isolated in a quadrupole ion trap and photoexcited with a UV tunable laser, resulting in the photodetachment of the excess electron. Whereas no influence of the proton on the UV spectrum of tryptophan was previously reported (Phys. Chem. Chem. Phys., 2004, 6, 2633; J. Chem. Phys., 2005, 122, 074310), we observe a strong bathochromism due to the presence of the negatively charged group in the vicinity of the chromophore. An excellent agreement with TD-DFT (time dependent density functional theory) predictions for the absorption spectrum of the lowest energy conformer is found. The sensitivity of the tryptophan chromophore to the presence of a remote negative charge offers new perspectives for charge mapping in large biomolecules.
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